MILENA gasification. Christiaan van der Meijden.

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1 MILENA gasification bed materials Christiaan van der Meijden

2 Overview MILENA gasification process Facilities Bed materials tested + results C l i Conclusions. Bed material topics of interest

3 ECN MILENA gasification technology low-n 2 product gas pyrolysis in riser BFB combustor biomass 1. Developed for high efficiency 2. Medium calorific gas, low N2 3. Complete conversion, no carbon in ash 4. High CH4 content, suitable for Bio- SNG production 5. Suitable for scale-up and pressurized operation 6. High tar content flue gas combustion ma3 -tevdaopld.p air ml..dr.pmlepsevrl3gp 5 2 ) 3

4 MILNEA 30 kwth Lab-scale installation More than 3000 hours of operation in gasification mode Tested fuels: Wood, sewage sludge, grass (not successful) and lignite. Bed materials: Olivine (Austria, Norway, Canada), dolomite (calcined and fresh) and Sand (+additives). 4

5 Lab scale MILENA + OLGA + SNG installation More than 2500 hours of operation in gasification mode since Tested fuels: Wood, sewage sludge, grass (not successful) and lignite MILENA OLGA Methanation gasification Gas cleaning 5

6 MILENA pilot plant Thermal input 160 kg/h (800 kw HHV) In operation since 2008 Connected to OLGA tar removal in Design fuel wood Gasifier / Riser diameter: 0.2 m Combustor diameter: 0.8 m Total height: 8 m Duration tests done with demolition wood and clean wood to generate engineering data for 12 MWth demo plant. Approx h of operation. 6

7 7 MILENA pilot fuel example

8 8 MILENA gas composition example

9 Bed material research in MILENA: Main goal: Preventing fouling in cooler between gasifier and gas cleaning (OLGA). OLGA performs well, no need for additional tar / dust removal. Tar dew point reduction preferably below 300 C C. No interest in reduction of light tars like naphthalene. No CH 4 reforming. Costs / bed material loss should be low. No negative effects on bed agglomeration

10 MILENA tests: Tested bed materials / bed additives: - Sand - Austrian olivine (limited) - Norwegian olivine (no thermal pretreatment), MILENA standard bed material. - Canadian olivine (Olimag, thermally pretreated). - Dolomite as additive - CaO as additive Note: Bed material testing was never a major topic, because tar removal is done by OLGA

11 Dolomite experiments: lab scale (30 kwth) Dolomite was tested because it is cheaper than olivine & is catalytically active Tests conducted: - 100% dolomite (CaCO 3 /MgCO 3 ) as bed material - Mixed with sand - Calcined dolomite (CaO/MgO) mixed with sand

12 Dolomite experiments: lab scale (30 kwth) Sand Dolomite 12% Dolomite/sand 6% Dolomite/sand 9% Cal. dolo./sand Tavg [ C] ~835 S/B [-] H 2 [vol%] CO [vol%] CH 4 [vol%] Tar class 5 [g/nm3 dr] Total tar [g/nm3 dr] Fines [gr/hr] n.m. 45 Remark: fines from combustor only. No producer gas cyclone in lab MILENA

13 Dolomite experiments: lab scale (30 kwth)

14 Dolomite experiments: lab scale (30 kwth) Dolomite is flash calcined when added to the hot bed, can result in pressure peaks & alarms 100% dolomite results is too much tar/carbon transport to the combustor and increasing temperatures 12% dolomite in sand results controlable temperatures and reduces tar Calcined dolomite: no CO 2 peaks

15 Olivine experiments: lab scale (30 kwth) 3 types of olivine tested: - Pretreated t olivine i from Austria and Canada - Untreated olivine from Norway

16 Olivine experiments: lab scale (30 kwth) Sand Olivine (No) Olivine (Au) Olivine (Can) Tavg [ ] S/B [-] ~0.35 H 2 [vol%] CO [vol%] CH 4 [vol%] Sum O CO 2 [vol%] Tar class 5 [g/nm3 dr] Total tar [g/nm3 dr] Note: duration tests were done with Norwegian olvine

17 Olivine experiments: lab scale (30 kwth)

18 Finding MILENA olivine experiments (1/2) Tar reduction is limited. Norwegian olivine is the worst option, but availability in right fraction is best. Pretreated olivine (sintered, migration of Fe to surface) reduces tar concentration and transports O 2 (typical between wt%). Untreated olivine, gets more active, over time during the reduction/oxidation cycles in MILENA.

19 Finding MILENA olivine experiments (2/2) Catalytic CO shift activity is influenced by air to fuel ratio in combustor. Despite bad performance Norwegian olivine is our standard in the lab and the pilot installation

20 Conclusions MILENA using sand or Norwegian olivine i produces a lot of tar (40 gram/nm3), OLGA can handle this. The sensitive part is the cooler. Despite the high tar concentration both the lab-scale and the pilot scale installation at run without fouling problems. Activity of Norwegian olivine is limited, better alternatives are available. Norwegian olivine has become our standard because of practical reasons. Bed materials remain a fuzzy subject. Measuring heavy tars is problematic. Addition of small amount of calcined dolomite looks promising, but pilot scale test failed because of flue gas cooler clogging

21 Bed material topics of interest Fundamental understanding olivine (Fe, Ca, etc.). Alternative ti bed material testing ti in indirect gasifiers (e.g. MgO). Additives testing in indirect gasifiers. Practical issues related to dolomite (gas coolers, calcination, etc.). Measurements of heavy tar concentration

22 MORE INFORMATION Christiaan van der Meijden e: PO Box 1 t: NL 1755 ZG Petten w: the Netherlands publications: fuel composition database: tar dew point calculator: IEA bioenergy/gasification: Milena indirect gasifier: l OLGA: / SNG: and 22 ECN 2012